Parametrically Generated Geometry of the Glass Metal Reinforcement Layer-paper-with Changes

8/19/2019 Parametrically Generated Geometry of the Glass Metal Reinforcement Layer-paper-with Changes

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1 INTRODUCTION

Glass has been known in the history of architecture since the ancient as the material with excep-tional transparency that is enabling parts of the buildings or building elements to transmit day-light into the interior of the buildings creating more intricate, humane and healthier interior liv-ing conditions. Its intrinsic transparency has enabled the border between inside and outside as a primary conceptual and spatial relation of the architectural object to be brought to its utmostdisappearance. The de-materialization of the solid envelope of the buildings by the use of glasshas rattled the imagination of the designers and architects ever since. The industrial revolutionand the development of novel components and technologies for production of the glass have re-inforced and broaden the possibilities for its architectural use. The use of glass for structuralelements has challenged the very basics of the architectural structures and esthetics inducingnew design philosophy and novel designs of building structures, envelopes and architectural el-

ements unprecedented in history of architecture.Today, the scope of the use of glass in architecture is highly extensive and hence the re-

quirements in the glass industry are growing bigger and more complex. The glass transparencywith minimum visual appearances of the structure has been set as the goals of the new glass el-ements for the building envelopes. The bigger transparency and designer’s strive for achievingthe ideal of “de-materialized” building envelope requires large glass formats. However, the useof large glass panels for architectural building envelopes has been challenged by constantlygrowing and changing structural, functional and esthetic demands for new and yet more func-tionally and structurally coherent products that will simultaneously provide structural integrityand innovative and unique architectural expression. At the same time there is clear prospectwhile developing new structurally comprehensive formats and shapes that further functionscould be achieved like energy efficiency, excessive radiation shielding, sight protection and

prevention from bird collision.

Challenging Glass 4 & COST Action TU0905 Final Conference – Louter, Bos, Belis & Lebet (Eds)

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Parametrically generated geometry of the glass metal

reinforcement layer

O. Marina Faculty of Architecture, Ss. Cyril and Methodius University, Skopje, Republic of Macedonia

B. Trajanoska Faculty of Mechanical Engineering, Ss. Cyril and Methodius University, Skopje, Republic of Macedonia

E. Filipovska Researcher, Skopje, Republic of Macedonia

ABSTRACT: Reinforcement of planar structural glass element has been explored with an addi-

tion of perforated thin metal layer adhesively bonded to the surface of the element in order toimprove load bearing capacity while preserving the required transparency of the element. Pla-nar glass elements have been modeled for their strength and distribution of forces in the casesof linear and point connection between the elements of the system and with continuous loads.The parameters of the force distribution within the element and the reaction of the element re-sulting in a unique pattern have been used to produce an algorithm that will generate an archi-tecturally specific and yet structurally supportive geometry of the glass reinforcement metallayer that is enhancing the load bearing capacity without compromising the transparency of theglass panel.


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Glass, under normal temperatures of service behaves as a linear elastic material that will break when tensile stresses exceed a critical value. The intrinsic tensile strength of glass is higheven in the cases when used as building elements. But the most prominent characteristic ofglass as a structural element is its brittleness causing the glass elements to collapse suddenly,without any residual post-failure strength due to the brittle way of fracturing and its propaga-tion through the whole element (Belis et al.; 2004). Thus, the main concept of enhancement of

glass structural capacity, especially when it comes to the glass planar elements, is to reinforcethe overall structural capacity by adding a supporting layer or lamination. This is usually done by combination of two materials developing a structural composite: individual or doubled glass plate and the reinforcement layer. The reinforcing layer could be used to enhance the load bear-ing capacity of the planar element or to introduce more plasticity in the structural behavior ofthe glass element and to enhance the post-breakage behavior of laminated glass (Feirabend etal.; 2009). The metal layer is added to the glass element usually perforated in order to providecertain level of transparency of the structural element. However, the use of standard perforatedmetal sheets although are adding to the load bearing capacity of the glass element, it is also re-ducing glass transparency and due to its standard formats of perforation it is limiting the archi-tectural expression of the glass metal reinforced elements.

This paper investigates the alternatives in process of design and application of the metal rein-

forcement layers to the glass planar elements through the change of the paradigm and introduc-tion of novel design philosophy.

2 DESIGN PHILOSOPHY

As the result of the process of revision of Modernism new concepts in architecture are based on phenomenology directly confronting with universal positivistic models of the past. With thisshift in paradigms and transcendence of concepts in architecture the interdependence of the in-herent nature of phenomena of form in architecture and the process of its creation has become anew challenge. Better understanding of the nature of the architecture as inherently dynamic andnot fixed typology is in the base of the new quest (Stavric & Marina 2010). Hence, the idea ofform in architecture will shift from a fixed typology toward a historically convergent result of a

form generating process, shaping unique result that is coherent to the nature and context of theform. The emerging form will be a result of a process of morphogenesis as a historically em- bedded process of creation, adaptation and optimization. With this shift in paradigms a theoret-ical ground for novel design tools and methods in architecture has been established like para-metric and algorithmic design.

Parametric design has come to the forefront of architectural practice, promising an increasedlevel of control over our projects as well as an incredible gain in the time used to generate solu-tions to given design tasks. Many tools exist which allow us to visualize the variations to a giv-en design based on a range of parameters and their associated consequences. Parametric designmeans working within parameters of a defined range. The parametric design links dimensionsand parameters to geometry thereby allowing for the incremental adjustment of a part whichthen affects the whole assembly. Algorithmic design refers to the use of procedural techniques

in solving design problems. Within the digital design algorithm refers to the design through thedirect manipulation not of form but of code. It lends itself to optimization and other tasks be-yond the limitations of standard design constraints.

New geometric patterns of the reinforcement metal layer has been produced using parametricdesign tools and the use of the code with clear intention to explore the structure of the rein-forcement metal layer that will be structurally legitimated and yet coherent with the functional,esthetic and ornamental requirements for the building glass envelopes. First the load bearingcapacity and the distribution of forces within the glass planar element has been investigated us-ing 4-point, 2-sided and 4-sided support. The resulting diagrams of distribution of forces has been used a s the basis for development of an algorithm that should generate an “appropriate”geometry of the reinforcement metal layer that should adapt to the distribution of forces and to provide additional support where it is needed. The resulting parametrically generated geometryof the reinforcement metal layer has been evaluated of its load bearing capacity through model-ing of the new glass-metal hybrid structure of the planar element and its newly gained structural


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capacity. It is foreseen that the used process of generation of adaptive geometric patterns of thereinforcement metal layer could enable production of innovative architectural design withunique and context sensitive patterns while enhancing the load bearing capacity of each of theelements of the building glass envelopes.

3

MODELLING GLASS PLATES WITH REINFORCEMENT METAL LAYER

The main objective of the patterned metal layer is its influence on the stress state of the glass panel subjected to pure bending, under out of plane wind load. In order to evaluate the functionof the metal layer models of the glass panel as well as the hybrid glass - metal panel were doneand analyzed using ABAQUS. In pure bending the load bearing capacity of the glass panelmostly depends on the strain and stresses that occur in the tensioned zone. For that matter, themetal layer is adhesively bonded directly to the glass surface that experiences tension under thesubjected load.

In the first state glass panels were modeled under the same perpendicular to surface load of1200 N/m2 and a different support conditions, simple support in four end nodes and ideal linearsupport on two shorter edges and four edges. Three different material models were used, all de-

fined with elastic mechanical properties, glass with Young`s modulus of 70 GPa, adhesive with603.5 MPa and steel with 210 GPa, and a Poisson’s ratio accordingly 0.22, 0.43 and 0.3.

Figure 1. Diagrams of stress state in the glass planar element (left side-top: 2 sides support, left side-down: 4 sides support, right side-top: 4 points support – back side, right side-down: 4 points support – frontside of the panel).

For the finite element analyses, 20-nodes brick elements were used for every model with a

finer mesh near the supports and the middle of the panel where highest strain/stresses were ex- pected. In order to decrease total elements number and cost of the model, it was simplified us-ing symmetry round two axes and only a quarter of the panel was modeled. Three different cas-es of the principle stress state were gained based on the provided support given as 2 sidesupport, 4 side support and 4 points support of the glass planar element.

4 PARAMETRICALLY GENERATED PATTERNS OF THE REINFORCEMENT LAYER

The tool used for generating the patterns of the reinforcement layer is Grasshopper, a graphicalgorithm editor, plug-in of McNeel’s Rhinoceros which is software used in architectural andindustrial design fields for three-dimensional modeling. This plug-in allows designers to build

form generators without any significant knowledge of scripting and programming. It uses geo-


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metric objects and mathematical functions as inputs and outputs for adjustments of parts whichthen affect the whole assembly.

Since the model is reinforcement of a structural glass element with thin metal layer adhesive-ly bonded, the support of the element, the loads and force distributions are the main inputs forgenerating a perforated pattern of the thin metal. For this process an additional Karamba plug-in is used, which makes it easy to combine parameterized geometric models and finite element

calculations. It generates a structural analysis model based on the generated Grasshopper ge-ometries.

Figure 2. Code for parametric generation of openings in the reinforcing metal layer.

The code starts with the constant parameters which define the dimension of the model set to1,2 / 3,2 m envisioning the glass element as a facade element. By setting the nodes and definingthe surface, through sets of numerical and mathematical expressions, the model goes for analy-sis performed by Karamba tools, connecting support and loads as elements of the structuralanalysis to the geometrically generated model. The main variable inputs which define differentways of perforations are the different ways of support of the model. We chose three differentscenarios were the panel is simply supported on its four end nodes, or an ideal linear support issupposed on the two shorter edges and on the four edges. The largest axial forces and the larg-

est resultant moments of all load-cases of the elements are used as main parameters for the fur-ther geometry defining process, creating the perforation. Three different panels with three dif-ferent types of distribution of perforation is the result of the parametrically generated models.

Figure 3. Parametrically generated geometric patterns and distribution of openings of the reinforcing metallayer based on the stress distributions in the glass planar element (left side-top: 2 sides support, left side-down: 4 sides support, right side-top: 4 points support of the panel).

5 EVALUATION OF THE NEW GLASS METAL HYBRID

After the parametrical study, three types of perforation of the metal layer were made which thanwere again tested in ABAQUS, this time as part of the hybrid glass – metal panels. The contact between the different materials was defined as tie constrains, master to slave surface. What wasobvious from the results (Figure 3) was the reinforcement that decreased the magnitude and in-fluenced the distribution of the stresses in the glass panel, which was the main objective at this phase of the research towards the mechanical characteristics of the new composite.


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Figure 4. Diagrams of stress state in the glass-metal hybrid element (left side-top: 2 sides support, left

side-down: 4 sides support, right side-top: 4 points support – back side, right side-down: 4 points support – front side of the panel).

Since the parametric design allows further control of the model by simply shifting the number sliders different outputs can be generated as number of perforations along x and y axis andthe dimension of the openings as well. The future work has been considered in exploration andgeneration of different shapes and geometries of the openings in the reinforcement metal layer,variation in the distribution of the openings, different thickness of the walls of metal layer be-tween the openings and exploration of various cases of load placement.

Figure 4. Different shapes and dimensions of the openings in the metal layer considered as the futureworks (left side: 2 sides support, middle: 4 sides support, right side: 4 points support of the panel).

6 CONCLUSION

Several geometries and distribution of openings in the reinforcing metal layer has been generat-ed as the result of the investigation and modeling of stress distribution in glass planar elements.The newly defined geometry is direct response of the code to the need for reinforcement in cer-tain parts of the glass panel. These bottom-up designs where the final geometry is not pre-determined but is rather emerging as result of interaction of many complex parameters is func-tion and context based. The new glass metal hybrid structure has been investigated for thestreets distribution in the newly defined hybrid. It is confirmed that the resulting geometry and patterns of the metal layer is adding to the load bearing capacity of the glass metal element withhigh level of transparency due to the size and distribution of the openings.

The use of parametric modeling and algorithms for generation of the geometry and distribu-tion of openings in the reinforcing metal layer in the glass metal hybrid has showcased that

there is huge potential for the future explorations of the possibilities to develop novel geome-


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tries as an individual and context sensitive response to the parametric of stress distribution, so-lar radiation control, energy efficiency and post-breakage safety. Parametrically generated andunique geometry of the metal layer could provide a useful tool for individualization of the glassmetal panels adding to the more creative and yet structurally coherent use of glass in architec-ture.

REFERENCES

Belis, J. et al. 2004. Key Engineering material, Glass structures and plasticity: contradiction or future?,Trans Tech Publications, Switzerland, (online available at www. scientfic.net), Vols. 274-276. 975 – 980.

Feirabend, S. & Sobek, W. 2009. Improved post-breakage behavior of laminated glass due to embeddedreinforcement, in Proceedings of Glass Performance Days 2009 Conference, Tampere Finland.

Stavric, M. & Marina, O. 2011. Parametric Modeling for Advanced Architecture, International journal ofapplied mathematics and informatics, Elektronische Ressource, 5, 1, S. 9 – 16.

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Parametrically Generated Geometry of the Glass Metal Reinforcement Layer-paper-with Changes